The goal of this project is to understand how clevage furrow divides a cell into two daughter cells. Both immunohistochemical and biochemical approaches will be taken to catalogue contractile proteins in the cleavage furrow so that we may understand the nature of the force producing machinary. Antibodies against various contractile proteins will be labeled with fluorochromes and used to determine with a light microscope which contractile proteins are localized in the cleavage furrow of tissue culture cells. By double antibody staining, the relative positions of two antigens will be studied simulataneously within one cell. Then using ferritin conjugated antibodies, ultrastructural localization of these contractile proteins will be determined in relation to the actin filaments which form the contractile ring. Cleavage furrows will be isolated from sea urchin eggs and analyzed by SDS-gel electrophoresis. I will also attempt to make a cell-free model system of a cleavage furrow. This model will be used to study the effects of ions, nucleotides and antibodies against various contractile proteins. It is hoped that the information obtained from this project will help understand the molecular basis for the function of the clevage furrow.